White Gold	Yellow Gold	Pink Gold	Green Gold

Gold is valued not just for its rarity, but also for its range of lovely colors, the distinctive character of its soft metallic glow, its resistance to tarnish, and its easy workability. Gold is so soft and malleable that one-ounce can be stretched into wire 50 miles long, or hammered into a sheet so thin it covers 100 square feet.  In its pure form, gold is a shiny yellow metal and is relatively inactive chemically.

In the karat system, pure gold is expressed as "24 karats fine" (24K).  The gold content of any gold article depends on the proportion of’ pure gold it contains.

Karat	Purity	Stamp
24K	Mininum 99.95% solid gold	999 or 9999
18K	18/24ths or 75% solid gold	18k, K18, 750
14K	14/24ths or 58.33% solid gold	14k, K14, 585
10K	10/24ths or 41.67% solid gold	10k, K10

The process of combining other metals (usually base metals) with gold is called "gold alloying," and the metals used in the process are usually called alloying elements.  The most common alloying elements used in the North America are silver, copper, nickel and zinc. Each of these metals alters the color, temper, hardness and annealing characteristics of the gold. Although the metallurgical relationship between gold and its alloying elements is quite complex, in general the degree of change, which can be imparted to the gold, is related to the percentage of base metal used. The higher the percentage of base metal use, the greater the change in the physical characteristics of the gold.

Jewelry gold range from light yellow through deep yellow to reds and greens, and also include a family of whites.

Silver:  As the proportion of silver increases, gold changes in hue from yellow to greenish-yellow, to white.

Copper:  As copper content increases, the gold becomes redder in appearance.

Nickel:  It has the effect of whitening gold.  The so-called "white gold" substitute nickel for silver.

Zinc:  It is considered a "decolorizer" and is used to convert red gold (copper alloys) into a more yellowish tone by substitute of zinc for some of the copper and silver.